1. Field of the Invention
The present invention relates to a rotary valve and, more particularly, to the rotary valve mechanism for a piston cylinder provided with one or more cylinders operating in a two-stroke or four-stroke cycle internal combustion engine.
2. Description of Related Art
In conventional internal combustion engines it is necessary to charge the cylinder with a fuel air mixture for a combustion cycle and to vent exhaust gases at the end of an exhaust cycle for each cylinder of the engine. In a typical piston cylinder engine, these events occur thousands of times per minute, per cycle. In conventional internal combustion engines, rotation of a camshaft causes spring loaded poppet valves to open and enable fuel/air mixture to flow from the carburetor to the cylinder in a combustion chamber during an intake stroke. The camshaft closes the intake valve during the compression and combustion stroke of the cylinder and opens a second spring loaded poppet valve, the exhaust valve, to evacuate the cylinder after compression and combustion have occurred. Exhaust gases then exit the cylinder and enter the exhaust manifold.
The spring loaded poppet valve assemblies include springs, rockers, guides, shafts and the valves themselves, mounted for reciprocating motion which reduces the energy output obtained by the engine. Manufacturing these poppet valves is costly due to the number and necessary precision of the mechanical parts involved.
As engine revolution increases, the poppet valves of course open and close more frequently. This demands tight tolerances and precise timing in order to prevent contact of the piston with an open valve. Thus, maintenance and adjustment is frequently required for the poppet valve engines.
The poppet valves themselves retain a great deal of heat during operation, and improper fuel detention may take place which results in a dieseling effect. One cure for such a problem is the use of more expensive, high octane fuel.
Rotary valves have been known for many years and are used in some engines in place of poppet valves to reduce the number of moving parts and reduce friction, thus increasing engine efficiency. However, in conventional rotary valves, it is common to have a metal-to-metal contact between the rotor valve and the and the cylinder which creates friction, thus increasing heat and reducing efficiency. Further, when ignition takes place, the explosion is typically exerted directly on the rotary valve. This can lead to sealing problems and may increase valve stress.